Cationic Derivatives Research Articles

Asymmetric trisalkylamine cyclopropenium derivatives with antimicrobial activity

Cationic molecules are found in abundance as antimicrobial agents with a well-defined mechanism of action and significant therapeutic benefits. Quaternary ammonium-containing compounds are frequently employed due to their facile synthesis and tunable properties. Over time, however, bacterial resistance to these compounds has become a significant obstacle. We report here a series of asymmetric trisalkylamine cyclopropenium cationic derivatives as chemical isosteres of quaternary ammonium compounds, capable of strong antimicrobial activity and overcoming microbial resistance. These small molecules were prepared by one-pot reaction of tetrachlorocyclopropene (TCC) with unhindered secondary amines in the presence of Hünig’s base. In this work we describe the synthesis, purification, and characterization of five trisamino-cyclopropenium derivatives and confirm their structures by spectral analysis and mass-spectrometry. Three of the compounds displayed considerable antimalarial activity (IC50 < 0.1 µM) without demonstrating significant toxic effects in vitro (TC50 > 1 µM). This class of cyclopropenium-based compounds provides an opening for the discovery of potent and non-toxic antimicrobial agents.

Single- and two-photon recording of holograms at combined cationic and free-radical polymerization photoinitiated by thioxanthenone derivatives

Single- and two-photon holographic recordings were performed in a photopolymer material consisting of two types of monomers: an acrylamide (1,4-bis(acryloyl)piperazine) and an epoxide ((bis(4-oxiran-2-ylmethoxy)phenyl) sulfide). Thus, cationic ring-opening polymerization and free-radical polymerization of the monomers were simultaneously initiated. The arylsulfonium salt (2-(N,N,N-triethylammonium)methyl-9-oxo-10-(4-heptyloxyphenyl)-9H-thioxanthenium dihexafluorophosphate) was chosen as the photoinitiator. Effective photopolymerization conditions were found for both (single- and two-photon) photoinitiation modes depending on the recording light intensity. The concentrations of the components (monomers and photoinitiator) in the photopolymer was optimized, and a refractive index change of as much as 0.0015 was achieved. Single- and two-photon holographic recording was investigated in photopolymer material consisting of two types of monomers: acrylamide (BAP) and epoxy (BOPS). Thus a cationic ring-opening polymerization and free-radical polymerization of monomers were initiated simultaneously. The arylsulfonium salt—cationic derivative of thioxanthenonium (CDTX) was chosen as the photoinitiator. The refractive index change n1 and maximum recording rate (dn1/dt)max of holographic gratings were found in two-photon photoinitiation modes depending on the concentration of BAP (the molar fraction of BAP) in photopolymer composition.

Use of a clay mineral and its nonionic and cationic organoclay derivatives for the removal of pharmaceuticals from rural wastewater effluents

A Na+ exchanged montmorillonite clay (Na–Mt) and its organoclay derivatives prepared with benzyldimethyltetradecylammonium (BDTA) cationic and polyoxyethylene (20)oleyl-ether (Brij-O20) non-ionic surfactants were used for first time at our knowledge as adsorbents the removal diverse pharmaceuticals (PPs) from samples collected in a rural wastewater facility (town of Josnes in France). The selected facility showed a poor efficiency for the elimination of PPs that were permanently release to the environment. Although involving different interactional mechanisms, the whole adsorbents Na–Mt, nonionic Brij-Mt and cationic BDTA-Mt organoclays, could remove the entire PPs of various chemical nature in a low concentration regime (ng L−1), where electrostatic interactions mainly controlled the adsorption. Thus, the organic PPs cations were preferentially adsorbed onto Na–Mt and Brij0.4-Mt (with its dual hydrophilic-hydrophobic nature) while anionic PPs showed a bold affinity to BDTA-Mt. The hydrophobic environment generated by the intercalation of surfactants within the interlayer space of organoclays conferred a versatility for the adsorption of numerous PPs through weak molecular forces (Van der Waals and/or pi-pi interactions). The study confirmed the proper efficiency of the studied layered materials including organoclays and emphasized about their promising interests in water remediation strategy.

Сationic carboxamide derivatives of tricyclic heteroaromatic compounds: synthesis and preliminary evaluation of antiproliferative activity

This research was aimed at the synthesis and study of biological activity of the carboxamides of tricyclic heteroaromatic systems, acridone, phenazine and thioxanthone, containing the aliphatic and aromatic cationic substituents at amide fragment. These heterocyclic cores are DNA intercalating agents, whereas the introduction of cationic groups provides additional ionic interactions of the ligands with their biological targets, such as DNA and enzymatic complexes of the system of nucleic acids biosynthesis. A convenient way of the introduction of such groups is a modification of heterocyclic carboxamides. A small library of new cationic amide derivatives of acridone-4-, phenazine-1- and thioxanthone-4-carboxylic acids was obtained. They were synthesized in 37-81% yield by mild and selective quaternization of the nitrogen atoms at N,N-dimethylaminoalkyl (alkyl = ethyl, propyl) and pyridylmethyl fragments of the neutral N-functionalized carboxamides with methyl iodide. Tricyclic heteroaromatic cores were not affected. Convenient protocol for the synthesis of thioxanthone-4-carboxylic acid (TCA) based on the reaction of 2-mercaptobenzoic and 2-iodobenzoic acids followed by cyclization of the intermediate was developed (yield 79%). A series of new N-functionalized neutral amides of TCA, the precursors of corresponding cationic carboxamide, were also obtained via the reaction of acyl chloride with amines. Preliminary in vitro testing of four compounds as potential antitumor agents in U87MG tumor cell culture (human malignant glioma) demonstrated their significant antiproliferative activity at low micromolar concentrations, with growth inhibition values GI50 in the range 1.7-11 µM. These results suggest that cationic carboxamides of tricyclic heteroaromatic systems are promising scaffolds for the design of new antitumor drugs.

The new water soluble zinc(II) phthalocyanines substituted with morpholine groups- synthesis and optical properties

Two new tetra- or octa-substituted zinc(II) phthalocyanines (1 and 2) bearing 3-(morpholinomethyl)phenyl groups were synthesized via Suzuki-Miyaura coupling method. These phthalocyanines (1 and 2) were converted to their water-soluble derivatives (1Q and 2Q) by quaternization of nitrogen atoms on the morpholine groups. The photochemical and photophysical properties of the non-ionic zinc(II) phthalocyanines (1 and 2) were explored in DMSO. On the other hand, these properties of the quaternized cationic derivatives (1Q and 2Q) were studied in both DMSO and aqueous solutions for determination of their photosensitizing capabilities in photodynamic therapy. The ct-DNA interaction of synthesized 1Q and 2Q were investigated and binding constants were found as 6.3 × 104 and 1.5 × 105 M, respectively. The binding constant values were found at similar levels of ethidium bromide (EB), which is a well-known intercalator. The spontaneous and exothermic nature of binding mechanisms were proved according to the calculated thermodynamic constants. Strong interactions of 1Q and 2Q with ct-DNA were also found with EB displacement assay and gel electrophoresis. Additionally, the bovine serum albumin (BSA) binding behavior of the new compounds (1Q and 2Q) were determined in water solution to verify the transporting capability of these phthalocyanines in the circulatory system and these values were found as 7.0 × 105 and 1.6 × 107 M−1 for 1Q and 2Q, respectively.

Blue moon ensemble simulation of aquation free energy profiles applied to mono and bifunctional platinum anticancer drugs.

Aquation free energy profiles of neutral cisplatin and cationic monofunctional derivatives, including triaminochloroplatinum(II) and cis-diammine(pyridine)chloroplatinum(II), were computed using state of the art thermodynamic integration, for which temperature and solvent were accounted for explicitly using density functional theory-based canonical molecular dynamics (DFT-MD). For all the systems, the "inverse-hydration" where the metal center acts as an acceptor of hydrogen bond has been observed. This has motivated to consider the inversely bonded solvent molecule in the definition of the reaction coordinate required to initiate the constrained DFT-MD trajectories. We found that there exists little difference in free enthalpies of activation, such that these platinum-based anticancer drugs are likely to behave the same way in aqueous media. Detailed analysis of the microsolvation structure of the square-planar complexes, along with the key steps of the aquation mechanism, is discussed.

P-N and N-Mo Bond Formation Processes in the Reactions of a Pyramidal Phosphinidene-Bridged Dimolybdenum Complex with Diazoalkanes and Organic Azides.

The reactivity of the complex [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(CO)2(η6-HMes*)(PMe3)] (1) toward different diazoalkanes and organic azides was investigated. The pyramidal phosphinidene ligand in 1 displayed a strong nucleophilicity, enabling these reactions to proceed rapidly even below room temperature. Thus, 1 reacted rapidly at 253 K with different diazoalkanes N2CRR' (R,R' = H,H, Ph,Ph, H,CO2Et) to give the corresponding P:P-bridged phosphadiazadiene derivatives as major products which, however, could not be isolated. Reaction of the latter with [H(OEt2)2](BAr'4) yielded the corresponding cationic derivatives [Mo2Cp{μ-κ1P:κ1P,η5-P(NHNCRR')C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4), which were isolated in ca. 70% yield. The related species [Mo2Cp{μ-κ1P:κ1P,η5-P(NMeNCHCO2Et)C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4) was isolated upon reaction of the ethyl diazoacetate derivative with MeI and subsequent anion exchange with Na(BAr'4). Reaction of 1 with aryl azides (4-C6H4Me)N3 and (4-C6H4F)N3 proceeded rapidly at low temperature to give possibly the corresponding P:P-bridged phosphaimine derivatives as major products, which could be neither isolated. Protonation of these products with [H(OEt2)2](BAr'4) gave the corresponding aminophosphanyl complexes [Mo2Cp{μ-κ1P:κ1P,η5-P(NHR)C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4), isolated in ca. 75% yield. In contrast, the result of reactions of 1 with benzyl azide was strongly dependent on temperature, including the temperature in the subsequent methylation step that gave isolable cationic derivatives. By a careful choice of experimental conditions, different complexes having methylated phosphatriazadiene ligands were isolated, such as [Mo2Cp{μ-κ1P:κ1P,η5-P(NNNMeCH2Ph)C5H4}(η6-HMes*)(CO)2(PMe3)](BAr'4) and the metallacyclic derivatives syn- and anti-[Mo2Cp{μ-κ2P,N:κ1P,η5-P(NMeNNCH2Ph)C5H4}(η6-HMes*)(CO)(PMe3)](BAr'4). Density functional theory calculations, along with NMR monitoring experiments, revealed that the formation of the latter products stemmed from different and kinetically favored phosphatriazadiene intermediates, thermodynamically disfavored with respect to the denitrogenation process, otherwise yielding phosphaimine derivatives.

Selective synthesis of N,N,N-trimethylated chitosan derivatives at different degree of substitution and investigation of structure-activity relationship for activity against P. aeruginosa and MRSA

Two new cationic chitosan derivatives were synthesized using a combination of Boc and TBDMS protection strategies. This included a series of six samples of the TMCNH2/TM derivative, where some of the amino groups were N,N,N-trimethylated and the remaining was in the primary state. A series of six samples of the TACin derivative, where some of the amino groups were N-acetylated with quaternary 2-(N,N,N-trimethylammoniumyl) acetyl group and the remaining fully N-acetylated, were also synthesized. The degree of substitution (DS) for quaternary amino groups in these series ranged from 0.06–0.89. TMCDM/TM derivatives with a mix of N,N,N-trimethylated and N,N-dimethylated groups were also synthesized according to a published procedure but in this case, it was more difficult to control the DS than with the TBDMS protection strategy.Broth microdilution assay revealed a markedly different structure-activity relationship (SAR) for the two derivatives. The activity for the TMC derivatives reached a plateau above 0.2–0.3 DS whereas the activity increased continuously with DS for TACin. The highest DS TMCNH2/TM was more active than the highest DS, TACin, against Gram-positive MRSA but less active against the Gram-negative P. aeruginosa.

Conjugated Polyelectrolyte Based Colorimetric Array for the Discrimination of Primary Amino Acids

AbstractWe report a colorimetric sensor based on the supramolecular complex between a conformation‐sensitive cationic polythiophene derivative, poly(3‐(4‐methyl‐3‐thienyloxy)propyltrimethylammonium) (PMTPA) and 2‐naphthalenesulfonate (NS). It could be applied to discern 19 primary amino acids by the wavelength of PMTPA/NS. The sensing performance and mechanism was investigated by spectroscopic studies such as absorption and emission spectra. This approach relies on the disassembly of PMTPA/NS aggregates induced by the amphiphilic isoindole derivatives of amino acids formed in situ. 100% confidence limits for this discrimination could be achieved by using linear discriminant analysis (LDA).

Cell-Modulating Effect of Poly(Aspartic Acid) and Its Complex with Cationic Polyaspartamide

In this communication, poly(aspartic acid) (pAsp), its fluorescently labeled conjugate with lucifer yellow ethylenediamine (pAsp–LY), and 2,2-dimethyl-1,3-propanediamine-derived cationic polyaspartamide (pDmpa) were synthesized by liquid-phase method. Octamer of L-aspartic acid (L-Asp8) was also obtained by solid-phase synthesis. pDmpa interacted with both pAsp and model plasmid DNA to form compact nanosized interpolymer complexes, which showed different colloidal properties. Effective cellular uptake of pAsp–LY by NIH 3T3 fibroblasts was detected by confocal microscopy. Pre-complexation of pAsp–LY with pDmpa did not noticeably increase intracellular accumulation of the conjugate. Both pAsp and L-Asp8 were found to increase viability of murine 3T3 cells and human skin fibroblasts at μg/mL concentrations according to the MTT assay (24 h). This effect was observed along with moderate prooxidant activity of the peptides in the cells according to the DCFDA fluorescence assay. The results suggest that aspartic acid-based peptides per se are capable of penetrating mammalian cells and affecting their metabolic activity. The peptides can be complexed with their cationic derivative, i.e., pDmpa polyaspartamide, to develop nanosized formulations of pAsp and its conjugates.

Group-Transfer Reactions of a Cationic Iridium Alkoxycarbene Generated by Ether Dehydrogenation.

Despite broad interest in metal carbene complexes, there remain few examples of catalytic transformations of ethers that proceed via alkoxycarbene intermediates generated by α,α-dehydrogenation. We demonstrate that both neutral and cationic alkoxycarbene derivatives are accessible via ether dehydrogenation at a PNP(iPr)4 pincer-supported iridium complex (PNP(iPr)4 = 2,6-bis((diisopropylphosphino)methyl)pyridine). Both cationic and neutral alkoxycarbene complexes undergo group transfer imination with azides, with the cationic derivative serving as a more efficient catalyst for cyclopentyl ether imination. Mechanistic studies support an iridium(I)dinitrogen complex as the resting state in the dark and a role for light-promoted N2 dissociation. Isoamyl nitrite and phenyl ethyl ketene are also found to engage with the cationic alkoxycarbene complex in formal alkoxide and O atom transfer reactions, respectively. In the former case an isolable dialkoxyalkyliridium complex is obtained, representing only the second example of a structurally characterized dialkoxyalkyl complex of a transition metal.

Hyperbranched cationic polysaccharide derivatives for efficient siRNA delivery and diabetic wound healing enhancement

Gene vectors are important for successful siRNA delivery. Four types of hyperbranched cationic polysaccharide derivatives (HCP) were synthesized by conjuncting 1,2-ethylenediamine (EDA) and diethylenetriamine (DETA) with glycogen or amylopectin respectively and named as G-EDA, G-DETA, A-EDA and A-DETA. The efficiency and safety of these HCPs to deliver siRNA were explored in vitro and in vivo. Our results showed that HCPs could form complexes with siRNA. All HCP/siRNA exhibited negligible cytotoxicity. Compared with A-EDA and A-DETA, G-EDA and G-DETA could carry much more siRNA into cells and then escape from endosomes. The delivery of MMP-9 siRNA (siMMP-9) by G-EDA and G-DETA significantly inhibited MMP-9 in HaCaT cells. Wound models in diabetic rats demonstrated that treatment of G-EDA/siMMP-9 could potently knock down MMP-9 of skin wound tissues and then enhanced wound healing. In summary, this study provided an effective and safe approach for siRNA delivery in vitro and in vivo.

An insight into the synthesis of cationic porphyrin-imidazole derivatives and their photodynamic inactivation efficiency against Escherichia coli

New porphyrin-imidazole derivatives were synthesised by Radziszewski reaction between 2-formyl-5,10,15,20-tetraphenylporphyrin 1 and several (hetero)aromatic 1,2-diones, which after cationization afforded promising monocationic photosensitizers 3a-d. Singlet oxygen studies have demonstrated that all the cationic porphyrin-imidazole conjugates 3a–d were capable to produce cytotoxic species. These photosensitizers were able to photoinactivate Eschericha coli and their inactivation profile was improved in the presence of KI.

Complexation of a cationic pyrene derivative with sulfobutylether substituted β-cyclodextrin: Towards a stimulus-responsive supramolecular material

Abstract The self-aggregation of the aggregation prone molecules are avoided by employing a macrocyclic host molecule, such as β-cyclodextrin, which commonly favours the inclusion complex formation with the guest molecule and prevents the self-aggregation of the guest molecule. On the contrary, the substituted host molecules, with multiple charges are reported to promote self-aggregation of guest molecules, specifically when the guest molecules are oppositely charged. One such interesting anionic host molecule is sulfobutylether substituted β-cyclodextrin (SBE7-β-CD), which possesses both extended hydrophobic cavity as well as relatively high negative charge which makes this host capable of forming both stable inclusion complexes with the incoming guest molecule as well as inducing aggregation of guest molecules. However, there are only limited reports of this host inducing aggregation of guest molecules. In the present work, we report the interaction of SBE7-β-CD with a versatile cationic fluorescent probe, 1-pyrenemethyl amine (PMA), using ground-state absorption, steady-state emission, and time-resolved emission measurements. Interestingly, in contrast to various reports, SBE7-β-CD is found to promote the aggregation of PMA molecules. These aggregates are confirmed by the changes in the emission spectra of PMA by emergence of a distinct broad emission band at around 493 nm, which is largely red-shifted from the monomer emission peaks of PMA which appear at 375 and 395 nm. The detailed investigation of the photophysical properties of this assembly discloses that association of PMA molecules in their ground-state is induced by SBE7-β-CD instead of forming excimers in the excited state. These aggregates are found to show significant and reversible response to external stimuli such as ionic strength of medium and temperature, which makes this system to be responsive aggregate assembly to be explored in sensing applications of biochemically important analytes, which has been demonstrated by sensing Lysine and Arginine, important basic amino acids, using this PMA-SBE7-β-CD assembly.

Folate receptor-targeted RNAi nanoparticles for silencing STAT3 in tumor-associated macrophages and tumor cells

We developed a STAT3 silencing siRNA to both tumor cells and M2 macrophages. The dual-targeting system prepared by electronic self-assembly was composed of folic acid-conjugated carboxymethyl chitosan for targeting and cationic chitosan derivatives for siRNA package. The effects of siRNA delivery was investigated in M2 macrophages and Lewis lung cancer cells (LLC). Due to the enhanced delivery efficiency, the dual-targeting delivery system exhibited a higher efficacy compared with non-targeting nanoparticles, resulting in a dramatically reduction of STAT3 expression in both cells, and a successful shift from M2 phenotypes (pro-tumor) to M1 phenotypes (anti-tumor) for macrophages. Additionally, the influence of the nanoparticles on LLC cells co-cultured with M2 macrophages was also investigated. The increased apoptosis and inhibition of proliferation of LLC cells were observed. In vivo therapeutic effect was also evaluated in s.c. tumor models, tumor growth was effectively inhibited and the level of M2 macrophages in tumor tissues was dramatically reduced.

Synthesis of Cationic Pyridinium–Chlorin Conjugates with Various Counter Anions and Effects of the Anions on Their Photophysical Properties

Abstract Cationic pyridinium pending chlorophyll-a derivatives with several counter anions were synthesized by Ag(I)-induced oxidation reactions of methyl pyropheophorbide-a possessing the 3-vinyl group with pyridine. The high water-solubility of the synthetic 31-pyridinio-3-vinyl-chlorin cation with a chloride anion resulted in efficient anion exchange reactions conducted in a biphasic system of H2O and CH2Cl2. Using either or both of the two synthetic procedures, ten salts were successfully synthesized with SbF6−, PF6−, BF4−, ClO4−, (CF3SO2)2N−, CF3SO3−, NO3−, I−, Br−, and Cl−. The effects of the counter anions on the physical properties of the cationic chlorophyll-a derivatives were discussed using their 1H NMR, visible absorption, and fluorescence emission data as well as theoretical model calculations. Although the visible absorption and fluorescence emission spectra were changed faintly, the fluorescence quantum yields and lifetimes were dependent on the counter anions, showing that the anions affected the pyridinium group acting as an electron-acceptor and the fluorescence quenching by intramolecular charge transfer.

Synthesis of cationic quaternized pullulan derivatives for miRNA delivery.

Pullulan is a natural polysaccharide of potential interest for biomedical applications due to its non-toxic, non-immunogenic and biodegradable properties. The aim of this work was to synthesize cationic pullulan derivatives able to form complexes with microRNAs (miRNAs) driven by electrostatic interaction (polyplexes). Quaternized ammonium groups were linked to pullulan backbone by adding the reactive glycidyltrimethylammonium chloride (GTMAC). The presence of these cationic groups within the pullulan was confirmed by elemental analysis, Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H NMR). The alkylated pullulan was able to interact with miRNA and form stable polyplexes that were characterized regarding size, zeta potential and morphology. The presence of miRNA was confirmed by agarose gel electrophoresis and UV spectrophotometry. In vitro tests on human umbilical vein endothelial cells did not show any cytotoxicity after 1day of incubation with nanosized polyplexes up to 200µg/mL. QA-pullulan was able to promote miRNA delivery inside cells as demonstrated by fluorescence microscopy images of labelled miRNA. In conclusion, the formation of polyplexes using cationic derivatives of pullulan with miRNA provided an easy and versatile method for polysaccharide nanoparticle production in aqueous media and could be a new promising platform for gene delivery.

In Vitro Amoebicidal Activity of Imidazolium Salts Against Trophozoites.

Several strains of the free-living genus Acanthamoeba can cause granulomatous amoebic encephalitis (GAE), a rare chronic and slowly progressive infection of the central nervous system (CNS), and Acanthamoeba keratitis (AK), a sight-threatening eye infectious disease. AK incidence has increased with the popularization of the contact lens wear and its treatment is currently limited and frequently unsuccessful. As imidazolium salts (IS), cationic imidazole derivatives, have promising antimicrobial potential. The present study evaluated the amoebicidal activity of four IS; 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16MImMeS), chloride (C16MImCl) and bis (triluoromethylsulfonyl) imide (C16MImNTf2 ), and 1-methyl-3-n-octadecylimidazolium chloride (C18MImCl), against the Acanthamoeba castellanii (ATCC30010) environmental strain and a clinical isolate (genotype T4). Three IS showed being lethal to 100% of the Acanthamoeba trophozoites at the minimum inhibitory concentrations of 125 and 62.5 μg/mL (C16MImMeS), 31.25 and 62.5 μg/mL (C16MImCl), and 125 and 125 μg/mL (C18MImCl) for ATCC30010 and isolate T4, respectively. C16MImNTf2 did not demonstrate amoebicidal activity. All active IS caused the hemolysis of erythrocytes. The cytotoxic effect of the IS was tested in RAW macrophages and human brain microvascular endothelial cells, which demonstrated cytotoxicity in all concentrations tested against both cell lines. As a consequence, these IS with amoebicidal activity presented low selectivity index values (SI) (SI < 1.0), demonstrating lack of parasite selectivity. Thus, C16MImMeS, C16MImCl, and C18MImCl seem to hold greater promise as components for contact lens cleaning and disinfection solutions, instead of direct human application.

A Review of Cationic Arylfurans and Their Isosteres: Synthesis and Biological Importance

The present study provides an overview of the chemistry and biological importance of the cationic chalcophene derivatives (furans, thiophenes and selenophenes). The summarized literature survey includes synthetic methods, reactivity and biological activities of aryl/hetarylchalcophenes that have been reported mainly from 2001 to 2019 focusing on monochalcophenes. A discussion demonstrating the proposed mechanisms of some interesting synthetic routes and linking structure features to biological activities is presented. These classes of compounds including cationic chalcophenes possess antiproliferative, antimicrobial and antiprotozoal activities. This review highlights recent advances for arylchalcophene derivatives and may contribute to the design and structure optimization of new chalcophene derivatives in the future.

Synthesis and Antioxidant Activity of Cationic 1,2,3-Triazole Functionalized Starch Derivatives

In this study, starch was chemically modified to improve its antioxidant activity. Five novel cationic 1,2,3-triazole functionalized starch derivatives were synthesized by using “click” reaction and N-alkylation. A convenient method for pre-azidation of starch was developed. The structures of the derivatives were analyzed using FTIR and 1H NMR. The radicals scavenging abilities of the derivatives against hydroxyl radicals, DPPH radicals, and superoxide radicals were tested in vitro in order to evaluate their antioxidant activity. Results revealed that all the cationic starch derivatives (2a–2e), as well as the precursor starch derivatives (1a–1e), had significantly improved antioxidant activity compared to native starch. In particular, the scavenging ability of the derivatives against superoxide radicals was extremely strong. The improved antioxidant activity benefited from the enhanced solubility and the added positive charges. The biocompatibility of the cationic derivatives was confirmed by the low hemolytic rate (<2%). The obtained derivatives in this study have great potential as antioxidant materials that can be applied in the fields of food and biomedicine.